This relates in general to the packaging art, and more particularly is concerned with a continuous reclosable plastic zipper of a type which is used to close the mouth of a bag.
In the use of plastic bags particularly for foodstuffs, it is important to have the bag hermetically sealed until the purchaser acquires the bag and its contents and takes it home and first opens the bag. It is then commercially attractive if the bag is reclosable so that the contents can be protected. Flexible plastic zippers have proven excellent for reclosable bags in that they can be manufactured with high speed equipment and are reliable for repeated reuse. A typical zipper is one which has a groove at one side of the bag mouth and a rib at the other side with the rib interlocking into the groove when the top of the bags are pressed together. Usually, pull flanges extend above the rib and groove strips, which flanges can be pulled apart for access to the bag. Such a fastener is popular, but does not prevent inadvertent or unwelcome opening within the store, and various additions have been made to provide tamper-evident seals which would disclose when the bag was improperly opened prior to purchase.
In spite of the fairly high state of development in this art, there are certain objectives which are still not fully met and there is room for the attainment of simplicity and economy in bags which require hermetic and tamper-evident reclosable closures for mouths of flexible bags.
It is accordingly an object of the present invention to provide a new and improved closure structure suitable for use for closing the mouth of flexible plastic bags which provides a hermetic seal until opened and thereafter affords the advantages and efficiencies of a typical reclosable rib and groove zipper closure.
A further object of the invention is to provide an improved rib and groove reclosable closure of a type particularly well suited for bags containing foodstuffs wherein a hermetic seal and tamper-proof arrangement is substantially integral with the rib and groove thereby reducing the amount of plastic film required for the closure, providing a better appearing, more efficient bag closure.
A still further object of the invention is to provide an improved flexible reclosable plastic zipper which has a unique construction that insures a hermetic seal and tamper-evident closure of the rib and groove until the intentional first opening of the bag and wherein the closure thereafter operates with full efficiency and effectiveness as a pressure reclosable rib and groove zipper closure.